Different types of apparatuses are known that make blood analyses swiftly and reliably. For example, the skin is lanced by means of a small, spring-mounted lancet, and the drop of blood from the skin is absorbed into a small, gauze dressing-like pad. The gauze dressing is normally attached to the centre of a narrow piece of plastic forming a so-called strip. In the plastic strip, there is a hole covered with a transparent or coloured film that penetrates light, whereto light is directed. By using a suitable strip and a calculation model, it is possible to define accurately, on the basis of the reflected colour, the blood property monitored each time, e.g., the glucose or cholesterol content.
A disadvantage of the apparatuses in question, particularly in long-term use, is that the measurements must be taken where the apparatuses are located, i.e., at home, at a workplace or at the doctor's. For example, for a diabetic, who has accurate medication times directly dependent on the glucose content of the blood, this is an impediment to a freedom of movement and living.